1. Field of the Invention
The present invention relates to a circuit for improving the frequency characteristic of a color television signal, and particularly of the chrominance component thereof.
2. Description of the Prior Art
The signal bandwidth of the chrominance component of a color television signal according to the NTSC system is 1.5 MHz and is narrower than the bandwidth of the luminance component which is about 4.0 MHz. Therefore, when the signal generated by a television camera is transmitted and demodulated in the receiver, the resulting color signals may not be reproduced in exact registration with the luminance component and blurring of the color image may result.
For purposes of illustration, if it is assumed that a received television signal represents the transition between a sharp-edged red primary color area and adjacent portions of a television picture, both the luminance component and the demodulated red color-difference signal should be step-shaped signals at such transition. However, due to the above noted limitation of the frequency band of the chrominance component, the desired step-shaped configuration of the color-difference signal is degraded to a more slowly rising or falling ramp signal. In contrast, the wider bandwidth of the luminance component permits a better approximation of the step-shaped configuration to be attained. Consequently, in a reproduced color television picture, there may be mis-registration of the color image with respect to the luminance image so that there is blurring or poor resolution of the color image.